BEIJING — The top U.S. admiral said Wednesday that friendly exchanges with China's navy are conditional on safe interactions at sea, an indication of Washington's concern over recent fractious encounters with Chinese forces in and over the disputed South China Sea.

On a visit to the northern Chinese port of Qingdao, Chief of Naval Operations Adm. John Richardson said he backs more exchanges, but added: "In this area we must judge each other by our deeds and actions, not just by our words."

"I am supportive of a continued and deepening navy-to-navy relationship, but I will be continuously reassessing my support conditioned on continued safe and professional interactions at sea," Richardson said, according to a Navy news release.

Richardson is on what they Navy called a five-day visit to improve mutual understanding and encourage professional interaction between the two navies. In Qingdao, he visited the headquarters of China's North Sea Fleet and met with its commander, Vice Adm. Yuan Yubai.

Richardson "underscored the importance of lawful and safe operations in the South China Sea and elsewhere where professional navies operate," the Navy said.

He said the U.S. Navy will continue to conduct "routine and lawful operations" around the world, including in the South China Sea, in order to protect "the rights, freedoms and lawful uses of sea and airspace guaranteed to all. This will not change," Richardson said.

He was also scheduled to visit China's first aircraft carrier, the Liaoning, along with a submarine training base.

On Monday, he met in Beijing with his Chinese counterpart, Wu Shengli, who took a hard line on China's claim to virtually the entire South China Sea, where China has been building airstrips, harbors and military facilities on man-made islands created by piling sand on top of coral reefs.

The U.S. refuses to recognize the new features as possessing the legal status of islands and has emphasized the point by sending Navy ships to sail close to them on so-called freedom of navigation missions. That has incensed China, which has responded by dispatching its own vessels to threaten and harass the U.S. ships.

Chinese planes have also engaged recently in what the U.S. described as unsafe maneuvering close to American surveillance aircraft.

Despite suspicions on both sides, U.S.-China military-to-military exchanges have steadily gained pace in recent years. China's navy is currently taking part for the second time in the Rim of the Pacific, or RIMPAC, the world's largest naval drills hosted by the U.S. off Hawaii and including military forces from 26 nations.

U.S. law limits the scope of U.S. military drills with China to areas such as search and rescue and humanitarian and disaster relief.

It's unclear what specific issues Richardson has discussed, but Wu told him China had no intention of abandoning its plans to fully equip its newly created islands and would resolutely defend its interests and sovereignty claims in the region. China has firmly rejected last week's ruling by an international arbitration panel in The Hague that essentially voided China's South China Sea maritime claims.